Communications network providers need to route traffic between many users. Failure to provide proper routing may result in sub-optimal network performance. Further, failure to properly record each communication session may result in the inability to maximize revenue by properly billing users for all such sessions. Thus, providers may wish to simulate a large number of possible communication sessions in order to identify and repair such failures before, rather than after, they have occurred. Because there are a large number of possible pairs of sender and recipient in such networks, need to evaluate many simulation scenarios.